There is need of brevity, that the thought may run on

In labouring to be concise, I become obscure.

Quidquid praecipies, esto brevis.

(Whatever advice you give, be brief.)

Brevity is the best recommendation of speech, whether in a senator or an orator.

Brevity is a great charm of eloquence.

I have made this letter longer than usual, because I lack the time to make it short.